Messages in this thread | | | Subject | Re: [PATCH 2/2] coresight: tmc: Add shutdown callback for TMC ETR/ETF | From | Robin Murphy <> | Date | Wed, 3 Jun 2020 14:40:52 +0100 |
| |
On 2020-06-03 13:26, Sai Prakash Ranjan wrote: > Hi Robin, > > On 2020-06-03 17:51, Robin Murphy wrote: >> On 2020-06-03 13:00, Sai Prakash Ranjan wrote: >>> Hi Robin, Mathieu >>> >>> On 2020-06-03 17:07, Robin Murphy wrote: >>>> On 2020-06-01 22:28, Mathieu Poirier wrote: >>>>> That being said I'm sure that dependencies on an IOMMU isn't a >>>>> problem confined >>>>> to coresight. I am adding Robin Murphy, who added this commit [1], >>>>> to the thread >>>>> in the hope that he can provide guidance on the right way to do this. >>>> >>>> Right, it's not specific to CoreSight, and it's not even specific to >>>> IOMMUs really. In short, blame kexec ;) >>>> >>> >>> Yes it is not specific to coresight, we are targeting this for all >>> consumers/clients of SMMU(atleast on SC7180 SoC). We have display >>> throwing >>> NoC/interconnect errors[1] during reboot after SMMU is disabled. >>> This is also not specific to kexec either as you explained here [2] >>> about >>> a case with display which is exacly what is happening in our system [1]. >> >> Sure, but those instances are begging the question of why the SMMU is >> disabled at reboot in the first place ;) >> > > That is what happens in SMMU shutdown callback right? It is the > reboot/shutdown flow.
Yes, that's where it happens, but my point is *why* it happens at all.
hint: `git log --grep=shutdown drivers/iommu/`
If we could assume the system is always about to be powered off or reset, we wouldn't need to do anything to the SMMU either ;)
Robin.
> > arm_smmu_device_shutdown() > platform_drv_shutdown() > device_shutdown() > kernel_restart_prepare() > kernel_restart() > > Thanks, > Sai >
| |